As Bill Gates announces he will leave his day-to-day role at Microsoft by July 2008, it signals an end to his running of the firm which has lasted over 20 years.

Mr Gates, who is planning on focusing on the foundation he and his wife founded, stresses that he is not retiring but simply making a transition.

Even though he will no longer be the CEO in two years time, as chairman he will maintain a key role in advising the firm.

1955: William Henry Gates is born in Seattle, Washington, on October 28 1955

1973: Enrols in Harvard to study computer science, but drops out during his third year

1975: Mr Gates founds Micro-Soft (later to become Microsoft) with his childhood friend Paul Allen on April 4 in Albuquerque, New Mexico.

1975 - 2000: Gates serves as chief executive officer for Microsoft

1979: The firm moves from Albuquerque to Bellevue, Washington; it later moves to Redmond, WA, where it still has its headquarters

1998: Antitrust Court case United States vs Microsoft

1999: Bill Gates' worth passes the $100bn mark

2000: Bill Gates and his wife Melinda found the Bill and Melinda Gates Foundation, an organisation focused on tackling global health and education problems

2000-2006: In 2000 Mr Gates assumes the title of chief software architect and stays on as company chairman; Steve Ballmer takes over as chief executive

2004: The European Commission fines Microsoft 497m euros (£339m, $627m) and forces it to offer a version of its Windows operating system without Microsoft's own media player

2006: Anti-competition hearing in which Microsoft appeals against the EU's 2004 ruling

2006: In June Mr Gates announces he will cease handling day-to-day operations by July 2008, although he will remain chairman of the firm. He says he will focus on running his and his wife's foundation.